Castello Ursino is a castle in Catania, Sicily, southern Italy.
Built circa from 1239 to 1250, it belonged to Emperor Frederick II, King of Sicily, and was considered impregnable at the time. In 1295, during the Sicilian Vespers, the Parliament which declared deposed James II of Aragon as King of Sicily, replacing him with Frederick III, was held here. The following year it was captured by Robert of Anjou but was later again in Aragonese hands.
King Frederick III resided in the castle, as well as his successors Peter II, Louis, Frederick IV and Maria. Here the latter was kidnapped by Guglielmo Raimondo III Moncada to avoid her marriage with Gian Galeazzo Visconti (1392). King Martin I held also his court in the castle.
After the move of the capital away from Catania and the appearance of powder weapons, the castle lost its military role and was used as a prison. It is one of the few buildings in Catania to have survived the earthquake of 1693. The castle has a rectangular plan, with a large circular tower at each corner and an open-air inner courtyard.
When the castle was first built, it was on a cliff looking out to sea, however as the result of volcanic eruptions, and earthquakes, it is now a kilometre inland. The former moat too in the 17th century was filled with lava from an eruption by Mount Etna. Its present location, surrounded by streets and shops in a typical Catania piazza, may strike some visitors as unusual.
Today the castle houses the Catania Civico Museum and a gallery of local art. On display in the museum are artifacts and artwork from the castle as well as the greater geographical area. These items date from the Classical era onward, representing the diverse influences throughout Sicilian history.